1. Field of Invention
This invention relates to paper clips which are removable, and preferably reusable, means of holding together collections of papers or other materials as well as serving as place markers in a book and/or locations on a page.
2. Prior Art
The most common paper clip, known as a Gem style configuration, originated about 1900. Its deficiencies include not lying flat when used with even modestly thick packets, unsuitability for use with thick packets, somewhat difficult to apply, weak gripping force with thin packets, tendency to dimple materials when left in place for any significant time, easily distorted, cut ends that can dig into and damage the surface sheets, etc.
These deficiencies, particularly ease of application and suitability for thick documents, have been addressed by other paper clip patents and product designs over the years. None however have offered sufficiently significant advantages to displace the Gem style as the dominant general purpose product design and only a relative few survive as niche products.
Comments on the products and patents most relevant to the instant invention follow:
Universal, Imperial and Ezeon style paper clips appear to derive from U.S. Pat. No. 1,344,473 Baldwin (1920). They consist of a relatively short, straight, central bridge leg connected to two near parallel and perpendicular side legs. Ending legs attached at the bottom of the side legs angle off at less than 45 degrees to the side legs and make one or more tangential contacts with the opposing side leg. Their central funnel mouth makes them easy to attach but as a group they have only a modest grip, easily distort and do not lie flat when used with thicker documents.
Ideal style paper clips are generally built in larger sizes and involve a relatively long, straight, central bridge leg connected to two crossing, diagonally angled side legs. The lower ends of these diagonal legs are coupled to two ending legs which Consist of a short vertical segment and a longer angled segment which crosses, but does not contact, its opposite member. Its forte is easy application to, and relatively good ability to lie flat with, thick packets. It also eliminates the risk of paper dimpling over time. However it is not suitable for general purpose use with only a few sheets due to its large size, limited gripping strength, and tendency to grip and pivot about only a single one of its crossing leg paths. Additionally the lower angled corners of the clip protrude substantially beyond the boundary of the opposing gripping jaw due to the crossing point of the the two side legs being approximately at the midpoint of the side legs. These protruding corners easily lift out of contact and can snag other pages.
U.S. Pat. No. 4,949,435 by Michelson (1990) has an objective of providing a paper clip that can stay flat when used with large packets of materials. However it has only limited gripping force for both thin and thick packets, its single pinch point and limited gripping footprint allows the clip to be easily dislodged, the clip and/or material being gripped pivots too easily, the ability to stay flat is limited and it has a similar excessive projection limitation as with the Ideal style.
U.S. Pat. No. 3,083,425 by Minnerly (1963) describes a clip geometry that is intended for gripping thick packets and provides for means to achieve a preloaded gripping action. However the design does not provide for sufficient elasticity between its gripping jaws, would not lie flat in its ready to use state and proposes a difficult to accomplish and control final folding action.